Ancient DNA extraction followed.

The extraction of ancient DNA is not a simple or guaranteed process.

Bone that has been in the ground for tens of thousands of years contains very little intact DNA — most of the original genetic material has been broken down by bacterial action, by water, by chemical processes that attack the molecular structure of DNA over time.

What remains are tiny, degraded fragments — short stretches of genetic code embedded in a much larger mass of bacterial DNA, environmental contamination, and chemical noise.

The process of extracting and sequencing this material requires specialized cleanrooms, where the researchers themselves must be excluded to prevent contamination from their own much more abundant modern DNA.